[FORGED] Re: identical() versus sapply()

On 09/04/16 16:24, Jeff Newmiller wrote:

I highly recommend making friends with the str function. Try

str( 1 )
str( 1:2 )

Interesting.  But to me counter-intuitive.  Since R makes no distinction
between scalars and vectors of length 1 (or more accurately I think,
since in R there is *no such thing as a scalar*, only a vector of length
1) I don't see why "1" should be treated in a manner that is
categorically different from the way in which "1:2" is treated.

Can you, or someone else with deep insight into R and its rationale,
explain the basis for this difference in treatment?

It's not the fact that one is a vector, it's just that the : function 
returns an integer result when given whole number arguments.  The 
literal 1 is stored in floating point, the result of 1:2 is integer.

I think the rationale is that sequences of whole numbers are often used 
as integers (e.g. in "for (i in 1:2)", whereas constants are often used 
in floating point expressions, so this reduces the number of conversions 
that are needed.  If you really mean your 1 to be stored as an integer, 
write it as 1L.  If you want it as floating point, write it as 1.

Duncan Murdoch